Bulk acoustic wave modes in quartz for sensing measurand-induced mechanical and electrical property changes

Citation
Rf. Schmitt et al., Bulk acoustic wave modes in quartz for sensing measurand-induced mechanical and electrical property changes, SENS ACTU-B, 76(1-3), 2001, pp. 95-102
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
SENSORS AND ACTUATORS B-CHEMICAL
ISSN journal
0925-4005 → ACNP
Volume
76
Issue
1-3
Year of publication
2001
Pages
95 - 102
Database
ISI
SICI code
0925-4005(20010601)76:1-3<95:BAWMIQ>2.0.ZU;2-3
Abstract
It is well known that a measurand in a gas, liquid or solid medium can caus e significant changes in the mechanical (mass, elasticity, viscosity) and/o r electrical (conductivity, permittivity) properties of the medium. In the case of quartz (alpha -SiO2) bulk acoustic wave sensors, the standard appro ach is to employ the AT-cut thickness-shear mode (TSM) to monitor the prese nce of the measurand. Although this mode exhibits excellent temperature sta bility and can operate efficiently in a liquid medium, it is not necessaril y the most sensitive mode to monitor mechanical and/or electrical changes i nduced by the measurand in the medium. It is the purpose of the present pap er to determine the sensitivity of the shear acoustic modes in various orie ntations in quartz so that one may choose the mode that is most sensitive t o the mechanical and/or electrical property changes caused by the measurand . The coupled elastic wave equation and Maxwell's equations are solved simu ltaneously to obtain five bulk and electromagnetic wave velocities and the associated mechanical and electrical fields quantities for the span of all doubly rotated orientations in quartz. Variational approximation techniques from prior studies are then used to predict the sensitivity of acoustic sh ear modes in doubly rotated quartz to measurand induced mechanical and elec trical property changes in the sensing medium. Those orientations and modes which are most sensitive to measurand-induced mechanical and/or electrical property changes in gas and liquid environment are identified. (C) 2001 El sevier Science B.V. All rights reserved.